1. Field of Invention
The present invention relates to the field of human hydration systems. In particular the present invention relates to a liquid dispensing valve for a human hydration system that improves performance in sustaining a column of liquid and enhanced performance. The present invention is particularly useful as a bite actuated liquid dispensing valve that is particularly advantageous for use in sub-freezing conditions.
2. Description of Related Art
Human hydration systems are used to hydrate or re-hydrate a person that is losing body fluids typically as a result of physical exertion, heat or a combination of the two. Prior hydration systems are generally constructed of a pliable soft liquid reservoir, a length of flexible tubing with the proximal end connected to the reservoir and a liquid dispensing unit connected to the tubing at the distal end. The liquid dispensing unit is generally constructed of a pliable material and is tube-like in design. The tube design has an open end that connects to the flexible tube and a closed end that contains through slits. The through slits are closed and must be opened by a biting action on the outer surface of the liquid dispensing unit which deforms the pliable material opening the slits. Once the slits open, liquid is drawn into the user's mouth by a sucking action.
Many hydration systems are designed to be transported on the back of the user. This places the liquid reservoir at an elevated distance above the liquid dispensing unit when the user is riding a bicycle or climbing at steep angles. This elevated position of the reservoir creates positive pressure in the liquid dispensing unit. If the liquid dispensing unit is incapable of containing the positive pressure, the liquid dispensing unit will leak often vacating the reservoir. Several liquid dispensing units in the prior art are designed to maintain static positive pressure under normal conditions.
For instance, U.S. Pat. No. 5,085,349 states that a positive static head of eight feet can be maintained with an initial wall thickness of 0.350 inch where the through slit is located. This is accomplished by using internal walls sloping at angles to the direction of fluid flow. U.S. Pat. No. 5,730,336 states that resistance to liquid flow is accomplished by a convex shaped inner wall in the liquid dispensing unit. In turn, a concave outer wall is used to allow pressure from outside the liquid dispensing unit to easily overcome the construction of the convex wall causing the through slit to open. In U.S. Pat. No. 5,791,510, FIG. 1 shows a partial diagram of a cyclist with a liquid supply at or below the level of the liquid dispensing unit. This patent describes a liquid dispensing unit that has an improved flow over previous dispensing units but is not capable of containing positive or negative pressure exerted on the dispensing unit.
Some liquid reservoirs, such as bottles and canteens, are located at an elevation lower than the liquid dispensing unit. The location of this type of reservoir creates several situations, as the liquid dispensing unit must hold a negative static column of liquid in the tubing that connects the liquid reservoir to the liquid dispensing unit. If this static column of liquid is not maintained the liquid will equalize returning to the liquid reservoir. For the user to obtain liquid from the reservoir, a sustained negative pressure, along with a biting action, must be applied to the liquid dispensing unit. This action creates a delay of liquid delivery and often frustration to the user. When the liquid dispensing unit is positioned lower than the fluid reservoir a positive static column of fluid is created. This can occur when the user is engaged in activities such as mountain climbing or camping.
Also, positive pressure is created in the fluid dispensing unit under such circumstances as when the fluid reservoir is compressed securing it into position, or when it is placed under sudden pressure as when a fall may occur trapping the fluid reservoir between the carrier and another surface. A liquid dispensing unit is preferred which is capable of maintaining a positive static pressure as well as negative static pressure of a liquid column without leaking fluid.
In addition to these concerns, another concern is low temperature freeze up of current liquid dispensing units. If a hydration system is used in a temperature range whereas water remains a liquid, generally no problems with the average liquid dispensing valve are encountered. In conditions where the temperature will fall below the freezing point of the liquid contained in the hydration system, the liquid dispensing valve will become inoperable due to the liquid contained in the liquid dispensing valve freezing and not allowing liquid to pass through the valve to the user.
Many hydration systems such as one known by the name PLATYPUS, utilize a means of attaching the fluid dispensing valve to the fluid tube by an annular internal friction connection. This type of connection creates a reduction in annular area of liquid to move through the connection. At this area of restricted liquid movement, liquid has a propensity to freeze faster than the remainder of the system since a smaller volume of liquid will loose heat faster to the freezing temperature. This is a ratio factor of a higher surface area to volume of liquid.
The so-called CAMELBACK hydration system uses a neoprene cover over the liquid delivery tube that extends from a liquid storage source to the liquid dispensing valve. The liquid dispensing valve, in turn, is covered by a temporarily removable foam insulating sheath that must be removed prior to withdrawing liquid from the dispensing valve. This system is cumbersome and does not permit hands free hydration since the foam insulating sheath that covers the liquid dispensing valve must be removed by the user with his hands prior to use.
When ice begins to form on the interior walls of all current liquid dispensing units, it may be dislodged from the interior walls by a biting action to the exterior walls of the liquid dispensing valve. An attempt of clearing or eliminating ice buildup from a current liquid dispensing valve often creates an ice damming effect, by creating ice shards too large to pass through the opening of the liquid dispensing valve. This damming effect of the ice hinders liquid flowing through the dispensing valve, eventually creating a complete freeze up condition of the liquid dispensing unit.
Water will freeze in a hydration system particularly in a liquid dispensing unit when subjected to temperatures below that which water remains a liquid in a static state. Since liquid contained in a hydration system, including the liquid dispensing unit, is generally in a static state, with the exception of liquid flowing through the system to the user for ingestion, the hydration system freezes becoming inoperable.
Based on the above and other problems with the relevant art, it is an object of the present invention to create a liquid dispensing unit that will maintain a fluid column in a delivery tube from a fluid reservoir to the fluid dispensing unit under a negative and positive static state of pressure on the liquid dispensing unit. Another object of the present invention is to create a liquid dispensing unit that will properly form and divide ice, forming within the liquid dispensing unit, into shards that creates a high ratio of surface area to volume. This will cause the ice shards to melt as liquid flows around them passing through the liquid dispensing unit.